The construction industry uses sheet metal in various ways. For example, sheet metal is used in ductwork, and as the exterior panels and roofing material of commercial buildings. As the speed of building increased, faster tools for quickly cutting the material were needed. There are several ways of cutting metal corrugated panels: with hand snips, power nibblers and power shears. On massive construction sites professionals use stationary industrial machines with blades designed to cut unique profiles.
Using circular saws is undesirable because they leave a cut edge without any treatments such as paint, zinc coating, or galvanizing. Shears, on the other hand, have a natural “edge sealing” effect, smearing the coating or treatment over the freshly cut edge. Shearing may be done with muscle power, as with tin-snips, or by an electrically or pneumatically powered tool that works similarly, but has greater power and speed.
Examples of portable powered shears to cut sheet metal are found in U.S. Pat. No. 2,635,335 to James, U.S. Pat. No. 4,173,069 to Sidenstick et al., U.S. Pat. No. 4,682,416 to Stolfa, and U.S. Pat. No. 7,093,365 to Peterson. U.S. Pat. No. 4,173,069 was assigned to Kett Tool Company, the assignee of the current application. 
U.S. Pat. No. 4,173,069 discloses a single moving blade, having two shear surfaces, working in cooperation with a fixed blade on either side, each of which has one shearing surface. U.S. Pat. Nos. 2,635,335, 4,682,416, and 7,093,365, on the other hand, use only one movable blade and one fixed blade.
Each of these devices can cut materials of various thicknesses with some level of success. Cutting flat sheet metal of low thickness (higher gauge numbers) is the easiest. However, the building industry continues to expand their use of metal corrugated panels. Corrugated panels are now more complex than early versions that had only rolling corrugations similar to the pattern found in common corrugated cardboard. Current corrugations are engineered in a variety of depths, shapes, and patterns. The pitch (spacing) between corrugations may be small or large. When viewed in cross-section, the corrugations may be trapezoidal, with sharp angles and deep valleys. Testing of portable shearing devices on the market reveals that they cannot cut all of the corrugated panels available. Therefore, a need exists for an improved tool, having the geometry and materials necessary to smoothly cut a greater variety of corrugated panels. Such a tool should be easy to use to make curved cuts, and ergonomically comfortable. Preferably the tool would bend the cut metal in a way that does not obstruct the tool, the user's hands, or the user's view of the cut.